Casting synthetic resins



CASTING SYNTHETIC RESINS Filed Feb. 8, 1960 INVENTOR JOHN MIL L/GAIV United States Patent cc. 3,132,195!

Patented May 5, 1964 1 2 3 132195 the component. A filler mixture is then streamed into the resin, made by tumbling 100 parts of dry sand, 4 parts CASTING SYNTHETIC RESINS of dimethyl phthalate, part of benzoyl peroxide and John Milligan, Blackpool, England, assignor to M.G.

3 I Plastics Limited, Blackburn, England A part Cychhexamne Pemxlde F] d F 8 1960 6 7 1 0 The filler is most suitably added to the resin as a stream Claims ermit; ap pliczition (5.5:: than r eb. 11, 1959 Preferably ihmugh mesh break up aggregates h' Claims. (CL 264 272) out so much buildp on the surface that the resm is blanketed with filler; in this way air release is facilitated. This invention relates to the casting of cold-setting A wide-mouth, meshed funnel has been found the most synthetic resins, that is to say, processes in which a liquid 10 satisfactory.

synthetic resin is fed into a receptacle and then caused The plotting operation just described is illustrated by to set by catalytic action without any substantial applicathe accompanying drawing. In this drawing, the sand, tion of heat. Such processes include not only the mould previously tumbled with the dimethyl phthalate, benzoyl potting process in which an 7 article generally an l receptacle 1 as a stream 2 into a wide-mouthed funnel 3.

trrcal component 18 embedded in the synthetic resin. This funnel incorporates a mesh 4 for the purpose of t is well known that Castlng can be eflected With liquid brcakmg p agglcmcratlcns m the funnel, the p epoxy or alkyd resins compounded with filler such as silica sand emerges as a stream 5 which is showed to how sand T 1s 1s a common method of potting, but generaly IIILO a y of liquid siylehaled alkyd resin 5 ly the resin has to be heat cured and entrained air has 20 housed ill a receptacle 0r P 7 within whieh all electrical to be removed in vacuo. The use of the relatively excomponent 3 is supported by means of stems lugs pensive, low-viscosity epoxy resins has gained ground be- The p sand fiews straight through the surface of the cause the alkyd resins (usually styrenated unsaturated resin and builds P as a lower layer 10 within the P 7 alkyds) shrink unduly, even after the heat-curing step The Operation is Completed when the p of the layer as been completed, 10 coincides with the top of the liquid resin 6, the resin An object of the invention i t bl casting to be then being filled with the sand whilst the electrical comeffected without the need for vacuum filling techniques Pelieili 8 is Completely embeddedand Without the need for curing at l d temperatures A feature of this invention is that robust vessels for the urther object is to enable potting, especially of trans resin are unnecessary for Potting Purposes Electrical formers, to be elfected with improved penetration or conjunctions and/or equipment can he Potted satisfactorily formity of the resin into or with the potted article using receptacles of flexible material such as p p p p The invention cons sts m a process of Castmg a co1d macho or thin plastic which can be made more cheaply setting synthetic resin which comprises feeding the liquid than the traditional Ceramic P p y he pp resm into a receptacle d th addmg through the temporarily with conformable material such as putty or P sed surface of the resin mi tu f heavy granular modelling clay. Individual joints may be potted before heavy here mean th t th wetted granular n should cation of heat where accelerated setting is desired, or in uence of the accompanying catalyst, h expression 1. A process of casting a cold-setting, solventless syninert means that the liquid does not int f r with the thetlc resin, which comprises feeding the liquid resin into catalyst or the catalysis of the polymerization process a receptacle and then adding through the eXPOSed surface and is itself not resinified to any substantial extent by the of the resin a mixture of heavy granular finer Catalyst catalyst. i and an inert liquid compatible with the resin, in which The preferred re i i a styrenated lk win The the inert liquid is present in an amount sulficient onl preferred filler i s d and may b used in an amount to wet the surface of the filler so that the mixture forms substantially to fill the resin, that is to say, to reach or a damp crumbly massnearly reach the resin surface on settling. The mixture A Process according to ciahn 1 hi which the resin 0 fille catalyst d li id may be prepared by tumbling comprises an unsaturated alkyd, the catalyst comprises an the ingredi nt Th li id may conveniently be a plasm organic peroxide and the inert liquid is a plasticiser for ciser for the resin. e resiil- In one example, 100 parts of unsaturated alkyd resin A Process according to claim 1 in which the filler and 25 parts of styren constitute the Casting resin; the is used in an amount sufiicient substantially to fill the ller mixture 18 made by tumbling 100 parts of dry sand resm 4 parts of a glycol ether ester plasticiser and 6 parts of A Process according to claim in which an electribenzoyl per d e. cal component is embedded in the resin.

It h b f d prefer bl h employing an alkyd 5. A process according to claim 1, in which the filler i to h present both the amine reactive type and mixture is streamed through the surface of the resin withthe cobalt-reactive type, with the respective accelerators. out blankefing said'surface- This enables widely 'diifering curing conditions to be A Process according to claim 5 hi which the filler catered for. A fu th example, using such a mixed mixture is streamed from asieving means resin, is as follows: 7. A process according to claim 4 in which said recep- One'hundred parts of a blended unsaturated styrenated iaeie is of fleXibie material alkyd resin containing both an amine-reactive type and a 8. A process according to l m 7 n Which i m cobalt-reactive type together with amine and cobalt acterial comprises paper or papier mach. i celerators (all as commercially available) are added to a A Process according to Claim 1 in Which the resin vessel (pot) housing an electrical component so as to employed is a blend of unsaturated styrenated alkyd peroxide and about /4 part of cyclohexanone peroxide.

reactive resin together with respective amine and cobalt References Cited in the file of this patent accelerators. a

10. A process according to claim 9 in which the filler UNITED STATES PATENTS 1,935,885 Merssner Nov. 21, 1933 comprises a blend of 180 parts of dry sand with about 4 parts of dimethyl phthalate, about partrof benzoyl 5 1,947,085 Hill et 131 1934 2,456,228 Weaverv Dec. 14, 1948 

1. A PROCESS OF CASTING A COLD-SETTING, SOLVENTLESS SYNTHETIC RESIN, WHICH COMPRISES FEEDING THE LIQUID RESIN INTO A RECEPTACLE AND THEN ADDING THROUGH THE EXPOSED SURFACE OF THE RESIN A MIXTURE OF HEAVY GRANULAR FILLER, CATALYST AND AN INERT LIQUID COMPATIBLE WITH THE RESIN, IN WHICH THE INERT LIQUID IS PRESENT IN AN AMOUNT SUFFICIENT ONLY 